1. Technical Field
The present invention relates to a manufacturing method and a manufacturing apparatus of optical goods such as a plastic lens.
2. Related Art
Traditionally, optical goods such as plastic lenses are manufactured by mixing a plurality of materials, injecting the mixture (referred to as a material composition hereinafter) into a mold and polymerizing the material composition within the mold. In order to manufacture optical goods of a constant quality, the progress of the polymerization reaction of the material composition is preferably controlled.
For instance, Document 1 (JP-A-2004-137481) discloses a preliminary reaction and deaeration processing that are conducted before a material composition is injected into a mold, where the progress of the reaction is detected by measuring a refractive index of a reacting composition. Specifically, an in-line refractometer is attached to a blend tank in which the preliminary reaction and the deaeration processing are conducted and a detector portion of the refractometer is always immersed in the reacting composition, so that the refractive index of reaction product is measured and monitored to control the progress of the blending operation.
Further, a usable time (referred to as a pot life hereinafter) after completion of the blending is designated for the material composition based on a result of an experiment in advance. The material composition that ran over the designated time is discarded.
However, when the material composition is managed based solely on the previously determined pot life irrespective of the condition of the material composition, the material composition may be used even after the condition of the material composition is degraded for some reasons, thereby deteriorating the quality of the manufactured plastic lens. On the other hand, even when the designated pot life of the material composition is elapsed, the material composition may still be usable in some cases. In such cases, the material is wasted.